Use of Oracle PL-SQL

Use PL-SQL

1. About PL-SQL（ function 、 Features and grammatical structure ）
2. data type （%type And %rowtype）
3.PL-SQL Control statement
4. exception handling
5. function

============================================

PL/SQL It's process language PL And structured query language SQL Combined programming language .
   PL/SQL Is aimed at Oracle Database ;
    It is a process language + The combination of structured query languages ;

    Process language PL： Such as variable declaration , Process control , Cycle, etc ;
    query language SQL：SQL Language , Ruzeng 、 Delete 、 Change 、 Check etc ;
 
   PL/SQL yes SQL The extended version of ,SQL What can be done ,PL/SQL Most of them can do .

PL/SQL The advantages of ：
   1. Support SQL： Data manipulation command , Transaction control command , slider control ,SQL Functions and SQL Operator ;
   2. Support for object-oriented programming ;
   3. Portability , Can run on any operating system ;
   4. After compiling and executing , Good performance ;
   5. And SQL Tight integration , Simplify data processing , Support SQL data type , Support NULL value , Support %type and %rowtype Attribute types （oracle The most interesting thing in ）;
   6. Security

PL/SQL It's divided into three parts ：
   1. Declaration part
   2. The executable part
   3. Abnormal schistosity

Grammatical structure ：
[declare declaration]  -- Declaration part
begin
    executable  statements  -- The executable part
    [exception  handlers]  -- Abnormal area
end;

Output ：
select 'abc' from dual;
dbms_output.put_line('abc');

    -- Printout ( Must bring begin)
    begin
        dbms_output.put_line('abc');
    end

assignment ：( := )
    -- Variable declaration assignment , And print
    declare i number(6);
    begin
        i:=77;   //:= assignment ,select...into It's also an assignment
        dbms_output.put_line(i);
    end;

-- stay emp The job number in the table is 7369 Name output for
declare sid number;
sname varchar2(22);
begin
    sid:=7369;
    select ename into sname from emp where empno=sid;  --select...into Assignment method
    dbms_output.put_line(sname);
end;

At the prompt ： stay begin with select sentence , Be sure to use select…into.

===========================================

data type ：
1. Scalar type
2.LOB type
3. Attribute types ：
  %type： Provide the data type of a variable or database table column
  %rowtype： Provide the record type of a row in the table ( Very distinctive )

3.1 %type

-- seek 7369 Date of employment ( Without knowing what type the column is )
-- Apply for one with “ Date of entry ” Same

declare sid number;
shiredate emp.hiredate%type;  -- Declare a variable , Its type is the same as that of a column in the table
begin
    sid:=7369;
    select hiredate into shiredate from emp where empno=sid;
    dbms_output.put_line(shiredate);
end;

-- It's fine too sb shiredate%type;

-- Ask for all the information about so and so
declare sid number;
sname emp.ename%type;
sjob emp.job%type;
begin
    sid:=7369;
    select ename,job into sname,sjob from emp where empno=sid;
    dbms_output.put_line(sname||'   '||sjob);
end;

Of course , If there are many columns in the table , Do you still write like this ？
NO, Use row type ：%rowtype;

-- Query all the information about so and so
declare sid number;
er emp%rowtype;
begin
    sid:=7369;
    select * into er from emp where empno=sid;
    dbms_output.put_line(er.ename||'   '||er.job);
end;

============================================

Input ：& （ Generally used for testing , Not much use in other cases ）

declare sid number;
er emp%rowtype;
begin
    sid:=& Please enter ;  --& similar scanner
    select * into er from emp where empno=sid;
    dbms_output.put_line(er.ename||'   '||er.job);
end;

  Be careful ：sid:=& Please enter ;  -- Represents that the input is an integer
    sid:='& Please enter '; -- On behalf of the input is varchar2 type .

=======================================
Logical comparison ：
<> , !=

=======================================

Control statement ：
if Conditions then
……
else perhaps elsif…then
……
end if

-- Wages are greater than 3500 pay taxes ,=3500 just ,<3500 Strive
if sentence ：
begin
  if sal>3500 then
      dbms_output.put_line(' pay taxes ');
  elsif sal=3500 then
    dbms_output.put_line(' just ');
  else
    dbms_output.put_line(' Strive ');
  end if;
end;

case sentence ：
case 
    when   then ;
    when   then ;
    else
end case;

Loop statement ： There are three kinds of ：
1.loop An unconditional cycle
2.while
3.for

-- Print 1~100
declare i number;
begin
    i:=1;
    loop
        dbms_output.put_line(i);
        i:=i+1;
        exit when i=100;    -- Exit and exit conditions
    end loop;
end;

============================================
declare i number;
begin
    i:=1;
    <<b_loop>>  --loop The name of the loop
    loop
        dbms_output.put_line(i);
        i:=i+1;
        exit b_loop when i=100;    -- Exit and exit conditions
    end loop;
end;
==========================================

-- seek 1~100 And
declare i number;
mysum number;
begin
    i:=0;
    mysum:=0;
    while i<=100 loop
        mysum:=mysum+i;
        i:=i+1;
    end loop;
    dbms_output.put_line(' The sum of the ：'||mysum);
end;

-- It will be used in the loop loop

--for The cycle of writing ：
declare
mysum number;
begin
    mysum:=0;
    for i in 1..100 loop
        mysum:=mysum+i;
    end loop;
    dbms_output.put_line(mysum);
end;

-- Find the sum of odd numbers
declare
mysum number;
begin
    mysum:=0;
    for i in 1..100 loop
        if mod(i,2)=1 then
        mysum:=mysum+i;
        end if;
    end loop;
    dbms_output.put_line(mysum);
end;

-- Sequential statements ：goto Label ……<< Label >>
Don't speak , A: no, no .

======================================
abnormal ：
1. System built-in exception --- Predefined exceptions
2. We write the exception of the codegram --- Custom exception

1. Predefined exceptions
  too_many_rows :   Too much
  no_data_found :   Data not found

Example ： Predefined exceptions ：
declare sid number;
shiredate emp.hiredate%type;
sb shiredate%type;
begin
    sid:=7369;
    select hiredate into shiredate from emp;
    dbms_output.put_line(shiredate);
-- abnormal
    exception  -- If an exception occurs, an error will be reported
    when too_many_rows then
    dbms_output.put_line(' Too much ');
end;

Example ： Custom exception
The three step ： Statement , Judge , capture

iee exception;

raise iee;

exception when iee then
    dbms_output.put_line(' error message ');
    when too_many_rows then
    dbms_output.put_line(' error message ');
    ……

     Multiple exception bodies can be carried

===============================================

function ：
create or replace function  f_name [( Parameters 1, Parameters 2..)]
return type
is/as  
     
[local declarations]  -- The variable declaration in the function body is placed in this position

begin
    -- Executor
    return 
    -- abnormal
end; 

-- Case study ： Number , Return salary ' pay taxes ' still ' just ', still ' Strive '
create or replace function f_n126(sid number)
return varchar2
is

    ssal number(8,2);
    str varchar2(22); -- Be careful , There is no need to declare Definition

begin
    select sal into ssal from emp where empno=sid;
    if ssal>3500 then
        str:=' pay taxes ';
    elsif ssal=3500 then
        str:=' just ';
    else 
        str:=' Strive ';
    end if;
    return str;
end;

-- How to call a function ？
--oracle Call mode ：
select f_n126(7369) from dual; 
 
--pl/sql Call mode ：
declare str varchar2(22);
begin
    str:=f_n126(7369);
    dbms_output.put_line(str);
end;

====== Custom exception =========================================
declare n_s number(5);
e_my exception;
pragma exception_init(e_my,-20001);
begin
    select count(stuname) into n_s from stuinfo where stuname like ' Zhao %';
    if n_s=0 then
        raise e_my;
    end if;
    dbms_output.put_line(' The number is '||n_s);

    exception 
        when e_my then
        dbms_output.put_line(' Personnel is empty ');
end;

===== function =================================================
create or replace function my_temp(n_s in varchar2, n_max in out number)
  return number is
  n_tavg number(5, 2);
begin
  select avg(stuage),max(stuage) into n_tavg,n_max from stuinfo where stuname like n_s||'%';
  return n_tavg;
end;

create or replace function my_sum(n_a in  number)
return number
is
n_sum number(5):=0;
begin

for int_s in 1..n_a loop
n_sum:=n_sum+int_s;
end loop;
return n_sum;
end;

Demonstrate basic usage   

--oracle-03  Built in functions 
-- Conversion function ：to_date  to_char  to_number
-- Date function ：sysdate|systimestamp|add_months|months_between|extract(year from sysdate)|last_day|next_day|round|trunc
-- String function ：lower|upper|ltrim|rtrim|lpad|rpad|chr|ascii|instr|substr|replace|decode|length
-- Mathematical functions ：abs|round|trunc|sign|mod|power|sqrt|ceil|floor
-----------------------------------------------------------------------
--oracle-04 PL/SQL Programming 
1.pl: Process language   
2.sql: Structured query language 
3.pl/sql  It is the combination of process language and structured query language .sql What language can achieve    pl/sql Can also be realized .
4.pl/sql What technologies are included in programming ？
 Printout , Variable usage , Selection structure , Loop structure 
5.pl/sql Combine ： Three part combination 
（1） Statement （ Definition ） part 
（2） The executable part 
（3） Exception handling part （ In the executable part of the package ）
 The second module is required , And the first and third are optional （ According to demand ）
6. grammar 
declare-- Declaration part 
      Property name   Attribute types ;
		 ....
begin--- The starting position of the executable part 
      utilize sql The result set obtained by the execution of the statement can assign the result to the above in a specific way declare In the defined variables .
		 
      Exception handling part 
	end;--- The end of the executable 		 




select sal from emp where empno = 7369;


-- demand ： adopt PL/SQL Program printout "zz is a nice man"
-- Printout ：dbms_output.put_line();---》 Sources and oracle Built in packages in 
begin
	dbms_output.put_line('zz is a nice man');
	end;

-- Define a variable to hold a name , Then print out 
declare
  sname varchar2(50);
	begin
		-- The assignment of a variable :=
		sname := ' Zhang San ';
		dbms_output.put_line(sname);
		end;
-----------------------------------------------
declare
  sname varchar2(50):=' rees ';
	begin
		dbms_output.put_line(sname);
		end;
-----------------------------------------------
-- Define multiple variables 
declare
  sname varchar2(50):=' rees ';
	ssex varchar2(2):=' male ';
	begin
		dbms_output.put_line(' My name is :'||sname||', My gender is : '||ssex);
		end;
		
--oracle Input device in     &  Wrapped in single quotation marks .
declare
  sname varchar2(50):='& Please enter ';
	ssex varchar2(2):=' male ';
	begin
		dbms_output.put_line(' My name is :'||sname||', My gender is : '||ssex);
		end;

-- Printout 7499 's salary .
declare
    myempno number:=7499;
		mysal number;
begin
    -- grammar ：  select aa into bb from  surface  	
		select sal into mysal from emp where empno =  myempno;
    dbms_output.put_line(' The salary is ： '||mysal);
	end;

-- Printout 7369 Your name and salary 
declare
    myempno number:=7369;
		myename varchar2(100);
		mysal number;
begin
    -- grammar ：  select aa into bb from  surface  	
		select ename,sal into myename,mysal from emp where empno =  myempno;
    dbms_output.put_line(' The salary is ： '||mysal||'   '||myename);
	end;
-----------------------------------------------------------------
PL/SQL Programming 2 There are two important types 	
 Attribute types  %type
 Line type   %rowtype    amount to oop The object of 
	
-- Printout 7369 's salary （ Uncertain type ）
declare
     myempno emp.empno%type:=7369;  -------  emp.empno%type => number
	   mysal emp.sal%type;
begin
	select sal into mysal from emp where empno = myempno;
	dbms_output.put_line(mysal);
	end;
	
-- Printout 7369 All properties of 
declare
     myempno emp.empno%type:=7369;  -------  emp.empno%type => number
	   myemp emp%rowtype;
begin
	select * into myemp from emp where empno = myempno;
	dbms_output.put_line(myemp.empno||'  '||myemp.ename||'   '||myemp.sal);
	end;	
	
-------------------------------------------------------------
# Selection structure    	if     case  
-- demand ： Determine whether a number is even 
declare
mynum number:=10;
begin
	if (mod(mynum,2)=0)  then
		dbms_output.put_line(' even numbers ');
	else
	  dbms_output.put_line(' Odd number ');
	end if;-- End selection structure 
end;	

-->3000  tax   =3000  Continue to work hard    <3000  Go home and raise pigs 
select ename,sal,
decode(sign(sal-3000),'1',' tax ','0',' Continue to work hard ','-1',' Go home and raise pigs ')
 from emp;

-- No learning cursor （ Courseware ）   Only one... Can be queried 
-- Judge 7369 At what level 
declare
myempno emp.empno%type:=7369;
mysal emp.sal%type;
begin
	select sal into mysal from emp where empno = myempno;
	-- Get mysal Just judge 
	if (mysal > 3000) then
		dbms_output.put_line(' tax ');
		elsif (mysal = 3000) then
			dbms_output.put_line(' Continue to work hard ');
			elsif(mysal < 3000) then
				dbms_output.put_line(' Go home and raise pigs ');
				end if;
	end;

--case   end  case

begin
         case 'F'
						when 'A' then dbms_output.put_line(' good ');
            when 'B' then dbms_output.put_line(' good ');
						 when 'C' then dbms_output.put_line(' commonly ');
						  when 'D' then dbms_output.put_line(' Okay ');
							else
								dbms_output.put_line('LOW');
								end case;
	end;

------------------------------------------------------
--loop   while    for

--loop loop 
/*
loop
	
	end loop;
	 And java Consistent with the dead cycle in   while(true){}

*/
declare
mynum number:=1;
begin
	loop
		dbms_output.put_line(mynum);--99
		mynum:=mynum+1;
		exit when mynum = 101;
		end loop;
	end;
--1-100 And 
declare
mynum number:=1;
mysum number:=0;
begin
	loop
		mysum:=mysum + mynum;
		mynum:=mynum+1;
		exit when mynum = 101;
		end loop;
		DBMS_OUTPUT.PUT_LINE(mysum);
	end;

-- name 
declare
mynum number:=1;
mysum number:=0;
begin
	    <<myloop>>
  loop
    mysum:=mysum + mynum;
    mynum:=mynum+1;
    exit when mynum = 101;
    end loop;
    DBMS_OUTPUT.PUT_LINE(mysum);
  end;

--while loop 
declare
mynum number:=1;
begin
	while (mynum<=100) loop
		dbms_output.put_line(mynum);
		mynum:=mynum+1;
		end loop;
	end;

--for The cycle is the simplest 
begin
	for i in 1..100 loop
		dbms_output.put_line(i);
		end loop;
	end;

-- abnormal 
1. Default meaning exception ： System given  no_data_found( No data exception found )   too_many_rows（ There are too many exceptions ）
2. Custom exception ：raise Throw an exception 
             （1） Define custom exceptions  exception
              (2)  Throw an exception after judging according to the requirements   raise
              （3） Catch the exception    exception



declare
    myempno number:=123;
		mysal number;
begin
    -- grammar ：  select aa into bb from  surface  	
		select sal into mysal from emp where empno =  myempno;
    dbms_output.put_line(' The salary is ： '||mysal);
		exception
			when no_data_found then
				dbms_output.put_line(' No data exception found （ The number provided does not exist ）');
	end;

--------------------
declare
    mysal number;
begin
    -- grammar ：  select aa into bb from  surface    
    select sal into mysal from emp;
    dbms_output.put_line(' The salary is ： '||mysal);
    exception
		when too_many_rows then
			 dbms_output.put_line(' There are too many exceptions ');
		when no_data_found then
				 dbms_output.put_line(' No data exception found ');
  end;


-- Query the salary of the specified number , If not 2000-5000 Between , Throw custom exception 
declare
myempno emp.empno%type:=7369;
mysal emp.sal%type;
myExceptionSal exception;
begin
	select sal into mysal from emp where empno = myempno;
	if (mysal < 2000 or mysal > 5000) then
		-- Throw an exception 
		raise myExceptionSal;
		end if;
		exception
			when myExceptionSal then
				dbms_output.put_line(' The unpaid salary is not within the specified range. Exception ');
	end;
------------------------------------------------------------------
-- function  function  effect ： One package, multiple uses 
/*
public void add(){

}


create or replace function  The name of the function ( parameter list )
return  Return type 
as|is
 Declaration part 
 The executable part 

*/
-- Packaging function   Find salary based on the specified number 
create or replace function getSalById(myempno emp.empno%type)
return emp.sal%type
as
mysal emp.sal%type:=0;
begin
	select sal into mysal from emp where empno = myempno;
	return mysal;
	end;

-- Call function 
select getSalById(7369) from dual;



--1-100 And 
create or replace function mySum(mynum number)
return number
as
sums number:=0;
begin
	for i in 1..mynum loop
		sums:=sums + i;
		end loop;
		return sums;
	end;

select mySum(10) from dual;


--  Recursive implementation of Fibonacci sequence No 21 The number of the item 
-- 1  1   2   3   5   8   13   21 .......
create or replace function diGuiDemo(mynum number)--3  diGuiDemo(1)+diGuiDemo(2)
return number
as
begin
	    if( mynum = 1 or mynum = 2) then
			    return 1;
			else
				return 		diGuiDemo(mynum-1)+diGuiDemo(mynum-2);
				end if;
	end;

select diGuiDemo(21) from dual;